1. Field of the Invention
The present invention generally relates to control signals contained within integrated circuitry and more specifically the voltage swing of the control signals.
2. Background Art
A form of communication among neighboring circuits is required to interface connected circuits contained within an integrated circuit. This mode of communication is in the form of logic signals based on the binary number system. The two symbols most commonly chosen to represent the two logic values taken on by binary signals are 0 and 1. For example, a circuit where the magnitude of its signals equal to either AVSS or DVDD can be assigned the symbol 0 to correspond to AVSS and 1 to correspond to DVDD, where the potential DVDD is generally the supply voltage of the circuit and the potential AVSS generally has zero potential corresponding to ground. Each circuit can require a different logic signal level then its neighboring circuits. For example, a circuit may operate with a logic “1” corresponding to 1.2 volts. A logic “1” corresponding to 1.2 volts can be insufficient to interface a neighboring circuit. To enable the neighboring circuit to recognize the 1.2 volt signal as logic “1” requires an amplitude shift.
Techniques are available to translate the magnitude of signal levels. One currently available technique is through the use of an intermediate circuit. This intermediate circuit translates the potential of one circuit's corresponding logic “1” into the potential required by a neighboring circuit. Thus the translated signal will have the same potential at logic “0,” ground, and the same potential at logic “1,” the level required by the neighboring circuit. For example, for a circuit operating with a logic “1” corresponding to 1.2 volts and a neighboring circuit operating with a logic “1” corresponding to 3 volts, the intermediate circuit will translate the potential of the 1.2 volt logic “1” into the 3 volt logic “1” of the neighboring circuit.
The potential difference between the minimum potential (i.e., logic “0”) and the maximum potential (i.e., logic “1”) is known as the logic swing of a signal. Using this technique of translating logic “1” of one circuit into logic “1” of a neighboring circuit while leaving logic “0” at the same potential for both circuits, generates a signal with a large logic swing. In some cases this large logic swing is unnecessary to interface a neighboring circuit; a signal with a lower logic swing will suffice. Resultant from this large logic swing is an unnecessary dissipation in power.
What is needed is an intermediate circuit with a reduction in logic swing that addresses one or more of the aforementioned shortcomings of conventional interfacing devices.